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Agriculture and Food 7–12 · Years 9–10

Incubating fertile eggs and candling the developing embryo

Animal Production 1

PracticalMedium risk

School laboratory, not for home

In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

The idea

A fertile egg develops into a chick over 19 to 21 days only while it is kept warm, humid and turned, and candling shows the embryo, its blood vessels and the growing air cell without opening the egg.

Safety card

Medium riskA teacher supervises

Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

Hazards

  • Salmonella and other bacteria on eggs, chicks and litter
  • heat lamp burns and fire
  • welfare of the chicks, including after the program ends

Controls

  • hand washing after every handling of eggs, chicks or equipment
  • heat lamp secured above the brooder and clear of bedding
  • no fertilised egg over 10 days old is held with the intention of disposing of it before hatching (prohibited by Animals in Schools)
  • fate of all chicks arranged before the eggs are set

Note

NSW Department of Education, Animals in Schools: activity categories and approvals under the Animal Research Act 1985 (NSW). A category 3 activity needs the school's Animal Welfare Liaison Officer to approve it; a category 4 activity needs the Schools Animal Care and Ethics Committee (SACEC) to approve student participation in writing; a category 5 activity needs SACEC certification, renewed every three years, for a teacher demonstration.

What you need

  • fertile hen eggs from a poultry supplier, 12
  • forced-air incubator with thermostat, humidity reading and automatic or marked hand turning
  • egg candler or a bright LED torch used in a darkened room
  • soft pencil, record sheet
  • brooder with a secured heat lamp, chick feed and water, for the hatched chicks
  • a written plan for the chicks' care and fate, including roosters, agreed before the eggs are set

How to do it

  1. Before starting, check the Animals in Schools requirements, plan weekend monitoring and the fate of every chick, and run the incubator for 24 hours at the manufacturer's settings to confirm it holds temperature and humidity.
  2. Mark each egg with an X on one side and an O on the other in pencil, and set the eggs.
  3. Turn the eggs as the manufacturer specifies (automatic turner or by hand), recording each turn, and record temperature and humidity twice daily.
  4. On day 7, candle each egg in a dark room: record eggs showing a dark embryo with radiating blood vessels and remove clear (infertile) eggs.
  5. Candle again later in incubation and trace the outline of the air cell on the shell to follow its growth; stop turning when the manufacturer's instructions say.
  6. Record the hatch day for each chick and calculate hatchability as chicks hatched divided by fertile eggs set, times 100.
  7. Move chicks to the brooder; for day-old meat chickens the Animals in Schools guidance gives 33 °C, lowered by 1 °C every 2 to 3 days to 20 °C at 28 days.

What you should see

At day 7 fertile eggs show a dark embryo with a spider-like network of blood vessels, and infertile eggs are clear. The air cell traced on the shell grows larger through incubation as water evaporates through the shell. Chicks hatch between day 19 and day 21, depending on breed, as the Animals in Schools breeding page states. The learner knows it worked when the day 7 candling result matches the eggs that hatch.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

  • Every egg from a farm could hatch into a chick.
  • The chick grows out of the yolk itself.
  • Eggs must be kept perfectly still to hatch.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

  • Agricultural Technology Years 7–10 Syllabus (2019)AG5-7AG5-10AG5-14
  • Agriculture Technology 7–10 Syllabus (2024), new syllabus, implementation from 2027AGT5-APG-01AGT5-SAF-01
  • Australian Curriculum v9AC9TDE10K04AC9S9U02

Sources

The pages the author read to write this activity.

  1. education.nsw.gov.au/teaching-and-learning/animals-in-schools/animals-in-schools-species/poultry-fowls/fowls-activities/fowls-breeding
  2. education.nsw.gov.au/teaching-and-learning/animals-in-schools/animals-in-schools-species/poultry-fowls/fowls-environment
  3. education.nsw.gov.au/teaching-and-learning/animals-in-schools
  4. www.nsw.gov.au/education-and-training/nesa/curriculum/tas/agricultural-technology-7-10-2019
  5. www.nsw.gov.au/sites/default/files/noindex/2025-09/agricultural-technology-years-7-10-syllabus-2019.docx
  6. curriculum.nsw.edu.au/learning-areas/tas/agriculture-technology-7-10-2024/outcomes
  7. education.nsw.gov.au/teaching-and-learning/animals-in-schools/animals-in-schools-compliance/categories-of-activities

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